Summer Survivors

During the hot, humid summer months, gardeners want plants that will flourish with little maintenance or care. At the University of Florida trial garden, we put the plants through their paces. Cultivars are planted in late March to early April and evaluated through the end of July. Our summer evaluation period is limited to June and July. This year, average temperatures were 91/68° F for June and 90/71° F for July, respectively. Even though we were below average for rainfall, we had almost 11 inches of rain in those two months. The end result was that we had plant material performing at the two extremes; many cultivars did not hold up throughout the summer, but a fair amount still looked very good. In late July, we selected the top summer performers and placed them into two “Best of Trials” categories: flowering and nonflowering.

In recent years, we have written about new crops with good heat tolerance (e.g., chrysocephalum ‘Flambe Orange’) or new cultivars from existing crops with much-improved heat tolerance (e.g., geranium ‘Caliente Coral’). This year, however, we trialed very few new crops, even though one-third of the entries were new 2009 introductions. Thus, most of our top performers are from crops with known heat tolerance. We will focus on new or recent introductions and why they stood out from the rest.

Begonia ‘Big Red Green Leaf’

The Begonia x benariensis Big series from Benary is new and consists of three cultivars. As the name implies, these plants have larger leaves and flowers than other fibrous begonias. The series is fairly uniform in growth habit and performance, but ‘Big Red Green Leaf’ was a bit more consistent throughout the evaluation period. By late July plants were more than 2 feet tall and had quarter-sized flowers. We did not see any problems with fungal leaf spot or stem collapse, even when it rained multiple times per week. ‘Big Red Green Leaf’ was grown in full sun and performed very well but can also tolerate filtered shade. Plants do not bulk up in size immediately, which allows for 4-inch production if the crop isn’t held too long after it is ready. In addition, it has great potential for larger-sized containers, such as gallons or large monoculture pots.

Begonia ‘Braveheart Rose Bicolor’

‘Braveheart Rose Bicolor’ from Syngenta Flowers, a standalone cultivar, was our top-performing begonia across the overall evaluation period. It has dark-pink bicolored flowers, and its burgundy stems and dark-green leaves are fuzzy to the touch. ‘Braveheart Rose Bicolor’ quickly filled its plot, was one of the first begonias to reach peak flowering and had a consistent show of color throughout the entire summer. As with ‘Big Red Green Leaf’, it did not show any of the fungal leaf spot or stem rot issues seen in many of the other begonias during the summer. This begonia was also planted in full sun and performed very nicely. It is more vigorous than many of the other fibrous begonias (similar in size to a Babywing begonia) and would look great as a mass planting in the landscape or a monoculture pot.

Caladium ‘Dr. Brent’

‘Dr. Brent’, a new caladium selection from the University of Florida breeding program, is a compact selection that performs well in either full sun or part shade. It has shiny rose-red strap leaves edged in dark green. All of the caladiums had a late start because of unseasonably cool weather in mid-April, but they started to grow and fill in as the season progressed. ‘Dr. Brent’ is similar in size to the Ruffles cultivars and is slightly more compact when grown in full sun as compared to 30 percent shade. The most noticeable improvement compared to existing cultivars is its fullness of habit, so it will be excellent when used as a border planting in the landscape or in a hanging basket. Also, because of its small stature, it will not tend to stretch out as much as other more vigorous cultivars if grown on tight spacing or in low light.

Coleus ‘Limon Blush’

‘Limon Blush’ is a new Proven Selections introduction available from Four Star Greenhouses. It has medium vigor and grew to about 3 feet tall by the end of July. It has deeply lobed peach-colored leaves with red veining and speckles of yellow, orange and green. ‘Limon Blush’ had very good self-branching, very little lower-leaf loss and a strong plant canopy that resisted lodging throughout the summer. It was one of the later cultivars to start flowering and did not have a noticeable number of inflorescences until mid-July. Its smaller growth habit and unique coloration make it a good selection for combination plantings, and it will not need a lot of growth regulators during production to keep its growth in check.

Colocasia ‘Elena’

‘Elena’, available from Agri-Starts I, defies the notion that bigger is better. It does not grow to 6 feet tall like other colocasias we have trialed but still reached a respectable 4 feet height after four months of warm weather. It is a slow grower under cool temperatures and did not start growing rapidly until the onset of summer. What ‘Elena’ lacks in height, it more than makes up for in overall appearance. It has chartreuse-green leaves and petioles plus a red dot where the petiole attaches to the leaf. This plant has leaves in abundance, resulting in a very full, dense canopy. Its smaller leaves handled thunderstorms better and had fewer shredded leaves and brown leaf margins compared to other colocasias in the trial. Its height and coloration lends itself to use as an accent planting in a small garden or by itself in a large patio container.

Ornamental Pepper ‘Calico’

‘Calico’ is one of three new ornamental peppers introduced this year by Ball Horticultural Company. It was designated a “Best New Variety” in our trial this spring for its performance in April and May, and it is now a “Best of Trials” selection for its performance during June and July. ‘Calico’ has a mounding growth habit; tricolored purple, white and green leaves; and dark-purple fruits that turn red as they mature. Its growth habit was very uniform, and it maintained a full appearance all season. One of the best attributes about this plant is that its attractiveness stems from both the foliage and fruit, thus requiring little — if any — maintenance for continued color interest throughout the season.

Pentas ‘Starla Appleblossom’

‘Starla Appleblossom’ is a new pentas cultivar from Goldsmith Seeds, one of seven entered in our trial from this two-year-old series. It is a good, uniform series in terms of growth habit and flowering potential. ‘Starla Appleblossom’ distinguishes itself from the other pentas in the trial with its unique flower coloration. The bicolored flowers have dark-pink centers and light-pink edges, but each flower has a slightly different ratio of the pink and rose shades. It flowered consistently all summer, even with a garden protocol of no deadheading. Pentas is a great summer crop in general, and now here is a new color option to add to the medium-height class.

Pennisetum ‘Princess’

‘Princess’ is an ornamental grass with purple foliage coloration that was entered in the trial by Emerald Coast Growers. It is a smaller version of ‘Prince’, with narrower leaves and a more compact growth habit. Don’t be fooled, though; it still has plenty of vigor! It filled its plot within four weeks of planting and reached about 4 feet tall by the end of July. ‘Princess’ can be planted much farther apart than our standard spacing of 12 inches, especially if standalone plants in the landscape are desired. It can be used as an accent plant in a landscape bed or by itself in a container. Having it in a combination planter can work if the pot is large enough so that ‘Princess’ has sufficient space and does not take over the other plants.

Salvia ‘Sarina Blue’

‘Sarina Blue’ from GroLink is another repeat selection from this year’s trial, selected as “Best of Trials” for both the spring (April and May) and summer (June and July) evaluation periods. Flowers are dark blue with a hint of white at the throat. The plants reached peak flowering in mid-May and maintained that level of flowering through the end of July. They have a very good self-branching habit and sturdy stems, which allowed them to maintain a full, upright appearance all summer. Plants grew to about 2 feet tall.

Scaevola Fairy series

The Fairy series of scaevola from Selecta First Class has three new colors: Blue evol., White and Violet. We evaluated all three in this year’s trial and they have very similar growth habits, with Violet being slightly more vigorous than the other two. They are a semicompact series, more compact than ‘Bombay Blue’ but not as compact as the Surdiva series. All had good flower coverage by late May and maintained this high level of flowering throughout the summer. The compact nature of this series will help keep them from getting too intertwined during production, and a light PGR application will help minimize that issue. Their semicompact nature lends them to basket production, and they will also function as low-growing plants in the landscape.

Jennifer Boldt, formerly trial coordinator at the University of Florida in Gainesville, is now graduate research assistant at the University of Minnesota in St. Paul. Jessica Boldt, formerly a graduate research assistant at University of Florida, is now with Pleasant View Gardens in Loudon, N.H. Jim Barrett is professor of floriculture, and Rosanna Freyre is a research scientist at the University of Florida in Gainesville, Fla. Jennifer can be reached at bold0120@umn.edu[4].